Bicycle Mechanics - Probably a daft uestion regarding a Rockshox rear shock unit

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DTM
10-20-06, 04:55 AM
Hi,
Can you tell me whether having removed the air shock from the rear end of my trek fuel mountain bike. I was suprised that the bottom damper half was able to rotate independantly of the top half, (I am not talking about the air can unscrewing. Just when I hold the top half of the aircan end, I can rotate the bottom shaft end within the top half, I know this is pretty irrelevent when its clamped up in the bike and the eyelets are parallel to each other. But I thought they would be locked in parallel position, Or not ? I was just concerned I was unscrewing something that might come loose later on.

Thanks in advance for any advice
Apologies if this is an obvious question, but I am pretty new to MTB suspension components

Pete Hamer
10-20-06, 09:23 AM
Hi,
Can you tell me whether having removed the air shock from the rear end of my trek fuel mountain bike. I was suprised that the bottom damper half was able to rotate independantly of the top half, (I am not talking about the air can unscrewing. Just when I hold the top half of the aircan end, I can rotate the bottom shaft end within the top half, I know this is pretty irrelevent when its clamped up in the bike and the eyelets are parallel to each other. But I thought they would be locked in parallel position, Or not ? I was just concerned I was unscrewing something that might come loose later on.

Thanks in advance for any advice
Apologies if this is an obvious question, but I am pretty new to MTB suspension components

That's normal. Nothing to worry about. It won't come unthreaded.
DTM
10-21-06, 03:58 AM
Ok, so then I assume that the top of the damper rod isnt threaded into the top cap

Pete Hamer
10-21-06, 09:41 AM
Ok, so then I assume that the top of the damper rod isnt threaded into the top cap


The damper rod is threaded into the top cap but not into the damper body. When you rotate the damper body independent of the air can like you are describing the damper rod is not rotating with the damper. The damper body is rotating around the damper rod and piston which is fixed to the top cap.

This is assuming that when we say "top cap" we are talking about the same thing.
I_bRAD
10-21-06, 10:21 AM
I'm not sure what all this top cap damper rod talk is but rotation is fine.

Think of it like a syringe- there's a piston in there (that's what the shaft is attached to- not the top cap) that seals against the edges of the cylinder but since it's round there's nothing stopping it from rotating. Which is fine, a non-rotating shaft is actually harder to make and there's no reason to when it's fixed at both ends.

This isn't a mtb shock, but all the priniples are there:

http://www.apracing.com/pics/cylinder/repair.gif